The Compensatory Potential Of Prefrontal Cortex Activation For Standing Balance In Older Adults With MCI

PURPOSE: This study aims to explore the characteristics of balance control and prefrontal cortex (PFC) activation in older adults with mild cognitive impairment (MCI) under single-task and dual-task paradigms compared with healthy older adults. METHODS: 21 older adults with MCI (MoCA: 18.33 ± 2.97) and 19 healthy older adults (MoCA: 26.47 ± 0.90) were recruited. Participants completed the balance task types of Bipedal Stance (BS), Bipedal Stance with Dual-task (BSD), Tandem Romberg Stance (TRS) and Tandem Romberg Stance with Dual-task (TRSD) respectively. Functional near-infrared spectroscopy (fNIRS) and force measuring platform are used to collect hemodynamic signals of the PFC and center of pressure (COP) data during the balance task, respectively. RESULTS: For balance control, two-way MANOVA showed the significant Group*Task interaction effect was found in 95% Ellipse area both under BS and BSD conditions (74.46 ± 17.09 vs. 167.60 ± 66.83 mm2, p < 0.001, 58.65 ± 14.28 vs. 167.60 ± 66.83 mm2, p < 0.001) and under TRS and TRSD conditions (281.33 ± 91.19 vs. 556.13 ± 175.17 mm2, p < 0.001, 272.20 ± 61.53 vs. 556.13 ± 175.17 mm2, p < 0.001). These showed that the MCI demonstrated worse balance control as compared to healthy older adults. For PFC activation, the significant Group*Task interaction effect was found in L10 (2.06 ± 5.63 vs. 13.10 ± 10.32 μmol/L, p < 0.001, 4.41 ± 10.08 vs. 13.10 ± 10.32 μmol/L, p < 0.001) only under TRS and TRSD conditions. The significant group effect was detected for L45 (p = 0.019), R45 (p = 0.003), R10 (p = 0.029), L46 (p = 0.003), and R11 (p = 0.010) under BS and BSD conditions. The significant group effect was detected for L46 (p = 0.043) and R46 (p = 0.028) under TRS and TRSD conditions. These showed that the MCI required higher PFC activation to maintain balance control when the balance tasks became difficult. Especially under TSD conditions, the MCI required more activation of L10. CONCLUSION: The MCI demonstrated worse balance control as compared to healthy older adults whether performing relatively simple or relatively difficult balance tasks. The greater activation of PFC under dual tasks in MCI may be considered a compensatory strategy for maintaining the standing balance.